On a lighter note....
1) Vampires, at least until someone can do something original with them. The whole S&M-tinged, "vampire as great lover" thing has been done to death. BO-ring.
2) Dragons, except as bit players as in Harry Potter.
3) Women with charming but selfish, usually alcoholic fathers whom they adore no matter how badly the fathers treat them, their siblings and their mothers.
4) Women with irresponsible hippie-type (if not actual hippie) mothers whom they must parent, and for whom they feel a mixture of love and exasperation.
(Note: Neither of these types of parents ever appear to have sons, or at least sons who appear as main characters in novels or memoirs.)
5) Bad puns in the titles of mysteries.
6) Whole mystery series built around crosswords, scrapbooking, gardening, etc., etc.
7) Books written in the present tense - something I have hated since the first one I read.
Well, that's all for now - I'm sure I'll think of more